dmaengine: fix cookie handling in iop-adma.c and ppc4xx/adma.c
Dan Williams said:
> > Russell King wrote:
> > Firstly, we have DMA_MIN_COOKIE which has value 1 - so any cookies below
> > that aren't valid. That seems sane.
> >
> > We seem to have different behaviours:
> >
> > - cookie = c->cookie;
> > - cookie++;
> > - if (cookie < 0)
> > - cookie = 1;
> > - c->cookie = cookie;
> > - tx->cookie = cookie;
> >
> > c->cookie here is initialized to zero, so the first cookie given out will
> > be 1. This is how most DMA engine drivers implement this.
> >
> > Then we have this:
> >
> > cookie = chan->common.cookie;
> > cookie++;
> > if (cookie <= 1)
> > cookie = 2;
> >
> > /* initialize the completed cookie to be less than
> > * the most recently used cookie
> > */
> > chan->common.completed_cookie = cookie - 1;
> > chan->common.cookie = sw_desc->async_tx.cookie = cookie;
> >
> > Again, chan->common.cookie starts off at 0. The first cookie given out
> > will be 2, and 1 will never be used. There are three drivers which
> > implement it this way.
> >
> > Why is there this difference, and can these three be corrected to behave
> > the same way as the first (and therefore the assignment of cookies
> > consolidated?)
>
> Yes, they should be consolidated, and I believe they have drifted only
> because there were no good common helpers and murphy's law took over.
So lets fix this up to use the common dma_cookie_assign() helper.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Tested-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Jassi Brar <jassisinghbrar@gmail.com>
[imx-sdma.c & mxs-dma.c]
Tested-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Vinod Koul <vinod.koul@linux.intel.com>
diff --git a/drivers/dma/iop-adma.c b/drivers/dma/iop-adma.c
index b1e3be08..4370b10 100644
--- a/drivers/dma/iop-adma.c
+++ b/drivers/dma/iop-adma.c
@@ -1622,16 +1622,12 @@
iop_desc_set_dest_addr(grp_start, iop_chan, 0);
iop_desc_set_memcpy_src_addr(grp_start, 0);
- cookie = iop_chan->common.cookie;
- cookie++;
- if (cookie <= 1)
- cookie = 2;
+ cookie = dma_cookie_assign(&sw_desc->async_tx);
/* initialize the completed cookie to be less than
* the most recently used cookie
*/
iop_chan->common.completed_cookie = cookie - 1;
- iop_chan->common.cookie = sw_desc->async_tx.cookie = cookie;
/* channel should not be busy */
BUG_ON(iop_chan_is_busy(iop_chan));
@@ -1679,16 +1675,12 @@
iop_desc_set_xor_src_addr(grp_start, 0, 0);
iop_desc_set_xor_src_addr(grp_start, 1, 0);
- cookie = iop_chan->common.cookie;
- cookie++;
- if (cookie <= 1)
- cookie = 2;
+ cookie = dma_cookie_assign(&sw_desc->async_tx);
/* initialize the completed cookie to be less than
* the most recently used cookie
*/
iop_chan->common.completed_cookie = cookie - 1;
- iop_chan->common.cookie = sw_desc->async_tx.cookie = cookie;
/* channel should not be busy */
BUG_ON(iop_chan_is_busy(iop_chan));